JP2003006838A - Laminated film for magnetic recording medium and magnetic recording medium using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated film having a lubricative coating layer suitable for a magnetic recording medium excellent in the flatness, the lubricative property, and the blocking resistance. SOLUTION: In the laminated film for the magnetic recording medium, in which the coating layer A is laminated on one side of a polyester film, the main component of the coating layer A consists of the elements of (1) an acrylic-polyester resin, (2) a cellulose derivative, (3) a crosslinking component consisting of an oxazoline compound having two or more oxazoline rings or an epoxy compound having two or more epoxy groups, (4) inert particles, and (5) a lubricant. The content of the (3) crosslinking component is equal to or more than 1 wt.% and equal to or less than 30 wt.% with respect to the weight of the coating layer A. The square average roughness (Ra) and the 10-point mean roughness (Rz) of the surface of the coating layer A that is not brought into contact with the polyester film by an AFM(atomic force microscope) are more than 3 nm and equal to or less than 20 nm, and equal to or more than 20 nm and equal to or less than 200 nm, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated film for a magnetic recording medium, and more particularly to a digital film for a digital video cassette tape or a data storage, which has no blocking during roll winding and has excellent electromagnetic conversion characteristics. The present invention relates to a laminated film useful as a base film of a ferromagnetic metal thin film type magnetic recording medium for recording data.

[0002]

2. Description of the Related Art A digital video tape for consumer use, which was put into practical use in 1995, has a magnetic metal thin film of Co provided on a base film and a diamond-like carbon film coated on the surface of the base film. Despite its smoothness, it has good durability. In addition, a back coat layer is applied to the non-magnetic surface side to provide good running properties. This consumer digital video tape is also used for computer data backup, and a data 8mm computer data backup device (Mammoth Exabyte, Sony AIT system) with a tape width of 8mm has been put into practical use, and it is small and has a large capacity. The transfer speed is fast and popular.

The base film is (1) a laminated film comprising a polyester film, a discontinuous coating adhered to at least one side of the film, and fine particles present in the coating and on the coating surface (for example, Japanese Patent Publication No. 62-301).
No. 05), (2) Laminated film which is a smooth polyester film and has a lubricant-based coating layer formed on the surface on the non-magnetic surface side (for example, JP-A-57-195321 and JP-B-1).
No. 49116, Japanese Patent Publication No. 4-33273) and the like are used, and a base film having a metal magnetic film forming surface roughness smaller than that of a base for a Hi8ME tape is used.

[0004]

However, even if these films can be easily handled in the film forming and processing steps, blocking between the films occurs when they are wound in a roll state, and unwinding of the rolls occurs. In stages,
The phenomenon that the film is cut or torn easily occurs.

It is considered that this blocking occurs because moisture in the air permeates the surface of the film or enters between the surfaces, and the pressure between the films causes the film to be in an adhesive state. Such blocking can be prevented to some extent by controlling storage conditions such that the roll-shaped product after film production or before use is controlled to have a low humidity, but it is not an essential solution. Particularly in the case of a flat polyester film for a vapor-deposited magnetic recording medium, it is very difficult to prevent the film from blocking only by controlling the humidity.

A polyester film which is easily blocked is easily charged when unwound from a roll. Then, the charged film, handling property during film formation and tape formation is significantly deteriorated, sparks may occur due to charging, there is a risk that the organic solvent used during tape formation may ignite, There is a problem that electrically floating dust in the air is adsorbed and a defect in electromagnetic conversion characteristics such as dropout occurs.

Therefore, the object of the present invention is to solve the above-mentioned problems, improve the slipperiness during film formation and processing while maintaining flatness, and have excellent blocking resistance during roll winding. Provided is a laminated film having a slippery coating layer suitable as a base film of a magnetic recording medium, particularly a magnetic film of a ferromagnetic metal thin film type for recording digital data for digital video cassette tapes, data storage, etc. Especially.

[0008]

According to the present invention, the object of the present invention is a film in which a coating layer A is laminated on one side of a polyester film, and the coating layer A comprises (1) acrylic-polyester. Resin, (2) cellulose derivative,
(3) At least one crosslinking component selected from the group consisting of an oxazoline compound having two or more oxazoline rings and an epoxy compound having two or more epoxy groups, (4) inert particles, and (5) a surfactant. And the content of the crosslinking component (3) is
Based on the weight of the coating layer A, 1% by weight or more and 30% by weight
And the root mean square roughness (Ra) and the 10-point mean roughness (Rz) by AFM of the surface of the coating layer A not in contact with the polyester film are larger than 3 nm and 20 nm or less and 20 nm or more and 200 nm or less, respectively. It is achieved by a laminated film for a magnetic recording medium, which is characterized in that

In a preferred embodiment of the present invention, (a) the content of the cellulose derivative is the coating layer A
5 wt% or more and 40 wt% or less based on the weight of (b) the content of the acrylic-polyester resin is 30 wt% or more and 9 wt% or more based on the weight of the coating layer A.
0% by weight or less, (c) the average particle size of the inert particles is 10 nm or more and 100 nm or less, and the content thereof is
3% by weight or more and 30% by weight based on the weight of the coating layer A
And (d) the coating layer A contains a resin having fluorine or a silicone compound as a copolymerization component in an amount of 1% by weight or more and 20% by weight or less, and (e) contacting the coating layer A of the polyester film. Not on the surface AF
The surface roughness Ra and Rz by M are each 0.1 n
m or more and 3 nm or less and 10 nm or more and 50 nm or less, (f) the polyester film is a film made of polyethylene terephthalate or polyethylene-2,6-naphthalene dicarboxylate, and (g) the thickness of the polyester film. But 2 μm
And less than 7 μm, (h) the surface of the coating layer A which is not in contact with the polyester film is the surface on which the ferromagnetic metal thin film layer of the magnetic layer is formed, and (b) the lamination for magnetic recording media. It also includes a laminated film for a magnetic recording medium, wherein the film is used for a magnetic tape of a digital recording system.

Furthermore, according to the present invention, there is also provided a magnetic recording medium using the above-mentioned laminated film for a magnetic recording medium.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION <Polyester> The polyester constituting the polyester film of the present invention may be any polyester as long as it forms a high-strength film by molecular orientation. Among them, polyethylene terephthalate and polyethylene-2,6-naphthalene are preferable. Dicarboxylate is particularly preferred.

The above polyesters include not only homopolymers but also those in which 80% or more of the constituents thereof are ethylene terephthalate or ethylene-2,6-naphthalene dicarboxylate. Ethylene terephthalate,
Examples of the copolymerization component other than ethylene-2,6-naphthalene dicarboxylate include diethylene glycol,
Propylene glycol, neopentyl glycol, polyoxyethylene glycol, p-xylene glycol,
Diol components such as 1,4-cyclohexanedimethanol, adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid (in the case of polyethylene-2,6-naphthalenedicarboxylate), 2,6-naphthalenedicarboxylic acid ( However, in the case of polyethylene terephthalate), a dicarboxylic acid component such as 5-sodium sulfoisophthalic acid and an oxycarboxylic acid component such as p-oxyethoxybenzoic acid can be used. The above polyester may be mixed with at least one of an alkali metal salt derivative of sulfonic acid which is non-reactive with the polyester component and a polyalkylene glycol which is substantially insoluble in the polyester, in a range not exceeding 5% by weight. Good. In any case, the ethylene terephthalate or ethylene-2,6-naphthalene dicarboxylate component is preferably 80 mol% or more, more preferably 90 mol% or more, and particularly 95 mol%.
The above is preferable. Further, a trifunctional or higher functional compound such as trimellitic acid or pyromellitic acid can be copolymerized. In this case, it is preferable to copolymerize the polymer in a substantially linear amount, for example, 2 mol% or less.

<Inert Particles> The polyester film of the present invention does not contain inert particles or has an average particle diameter of 0.03 μm or more and 1.0 μm even if it is contained.
The content of inert particles having a particle size of 0.05 μm or more and 0.3 μm or less is 0.5% by weight or less, more preferably 0.2% or less.
It is preferably not more than weight%. Average particle size is 1.0μ
If it exceeds m or the added amount exceeds 0.5% by weight, the electromagnetic conversion characteristics tend to deteriorate, while if the average particle size is less than 0.03 μm, the particles tend to aggregate. The inert particles to be contained may be organic particles or inorganic particles, and as the organic particles, polystyrene, polystyrene-divinylbenzene, polymethylmethacrylate, methylmethacrylate copolymer,
Methyl methacrylate copolymer crosslinked, polytetrafluoroethylene, polyvinylidene fluoride, polyacrylonitrile, particles made of a polymer such as benzoguanamine resin, and core-shell structured particles made of a graft copolymer containing these polymers as preferred examples. Preferred examples of the inorganic particles include particles made of an inorganic compound such as silica, alumina, titanium dioxide, feldspar, kaolin, talc, graphite, calcium carbonate, molybdenum disulfide, carbon black, and barium sulfate.

These particles are usually used in polyester production.
For example, it is added to the reaction system at any time during the transesterification reaction or polycondensation reaction in the case of the transesterification method, or at any time during the direct polymerization method, preferably as a slurry in glycol.

The polyester film in the present invention may be a film having a single layer structure or a film having a multilayer structure of two or more layers formed by a coextrusion method or the like. In the case of a multilayer film, the polyester of the surface layer (magnetic layer surface) on which the magnetic layer is formed contains substantially no inert particles,
Alternatively, even if it is contained, it is preferably within the range of not exceeding 0.5% by weight, more preferably not exceeding 0.2% by weight. Further, the polyester on the opposite surface, that is, the surface layer (nonmagnetic layer surface) on the side where the magnetic layer is not formed is 0.05
The content of the inert particles may be in the range of wt% to 0.8 wt%, and more preferably 0.1 wt% to 0.3 wt%. The root mean square roughness (Ra) by AFM of the outer surface of the coating layer A is 3
It is preferable to select it so as to be larger than 20 nm and not larger than 20 nm. In the present invention, the AFM is used for convenience of explanation.
The root-mean-square roughness according to is called Ra, and the 10-point mean roughness is called Rz.

<Coating layer A> In the present invention, the coating layer A laminated on one side of the polyester film is (1) acrylic-polyester resin, (2) cellulose derivative,
(3) At least one cross-linking component selected from the group consisting of an oxazoline compound having two or more oxazoline rings or an epoxy compound having two or more epoxy groups, (4) inert particles, and (5) a surfactant. The component consisting of is the main component.

The proportion of the acrylic-polyester resin (1) in the coating layer A is preferably 30% by weight or more and 90% by weight or less, more preferably 40% by weight or more and 75% by weight or less. If this proportion is less than 30% by weight, the adhesion to the polyester film will decrease and the coating layer will be easily scraped. On the other hand, the acrylic-polyester resin (1)
When the ratio of the above in the coating layer A is more than 90% by weight, the ratio of the component (2), (3), (4) or (5) is excessively decreased, and the tape characteristics and the coating property of the coating layer A are reduced. Cause trouble.

By the way, the polyester component in the acrylic-polyester resin (1) secures the adhesiveness between the coating layer and the polyester film, and the acrylic resin component secures the abrasion resistance of the coating film and the oligomer suppressing effect of the base film. Therefore, the molar ratio of polyester component / acrylic resin component is 1/9 or more and 5/5 or less, preferably 2/8.
It is preferably 4/6 or less. This ratio is 1/9
When it is less than 5, the adhesion of the coating layer A to the polyester film tends to be insufficient, while when it exceeds 5/5, the coating layer A is
The abrasion resistance and the oligomer suppressing effect of the base film tend to be poor.

The term (1) acrylic-polyester resin is used to mean an acrylic-modified polyester resin or a polyester-modified acrylic resin, and the acrylic resin component and the polyester resin component are bonded to each other. And includes, for example, graft type and block type. Such an acrylic-polyester resin is, for example, a radical initiator is added to both ends of polyester to polymerize an acrylic monomer, or a radical initiator is added to a side chain of polyester to polymerize an acrylic monomer. Or by attaching a hydroxyl group to the side chain of the acrylic resin and reacting with a polyester having an isocyanate group or a carboxyl group at the terminal.

The polyester component constituting the acrylic-polyester resin comprises a polybasic acid component and a polyol component. Examples of the polybasic acid component include terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride, 2, 6
-Naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, adipic acid, sebacic acid, trimellitic acid, pyromellitic acid, dimer acid, 5-sodium sulfoisophthalic acid and the like are preferable. These acid components are usually composed of two or more kinds, and may contain hydroxycarboxylic acid components such as unsaturated polybasic acid components such as maleic acid, itaconic acid and p-hydroxybenzoic acid in a slight amount. Further, as the polyol component, for example,
Ethylene glycol, 1,4-butanediol, diethylene glycol, dipropylene glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, xylene glycol, dimethylolpropane, poly (ethylene oxide) glycol, poly (tetramethylene oxide) ) Glycol and the like are preferred. Two or more of these polyol components can be used. These polyester components can be produced by reacting the above-mentioned polybasic acid or its ester-forming derivative with the above-mentioned polyol or its ester-forming derivative by a conventional method.

The component of the acrylic resin constituting the above acrylic-polyester resin is not particularly limited, but as the acrylic monomer, for example, acrylate ester (alcohol residue is methyl group, ethyl group, n-
Examples thereof include propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, phenyl group, benzyl group and phenylethyl group. ); Methacrylic acid ester (alcohol residue is the same as the above acrylic acid ester); 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2
-Hydroxy-containing monomers such as hydroxypropyl methacrylate; acrylamide, methacrylamide,
Such as N-methylmethacrylamide, N-methylacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, N, N-dimethylolacrylamide, N-methoxymethylacrylamide, N-methoxymethylmethacrylamide, N-phenylacrylamide, etc. Amido group-containing monomers; amino group-containing monomers such as N, N-diethylaminoethyl acrylate, N, N-diethylaminoethyl methacrylate and the like can be mentioned.

These monomers may be used alone or in combination of two or more, but styrenesulfonic acid, vinylsulfonic acid and salts thereof (for example, sodium salt,
Monomers containing sulfonic acid groups or salts thereof such as potassium salts, ammonium salts, etc .; crotonic acid, itaconic acid, acrylic acid, maleic acid, fumaric acid, and salts thereof (eg sodium salt, potassium salt, ammonium salt) Etc.) etc., a monomer containing a carboxyl group or a salt thereof; a monomer containing an anhydride such as maleic anhydride, itaconic anhydride, etc .; other vinyl isocyanate, allyl isocyanate, styrene, vinyl methyl ether, etc.
Monomers such as vinyl ethyl ether, vinyl trisalkoxysilane, alkyl maleic acid monoester, alkyl fumaric acid monoester, acrylonitrile, methacrylonitrile, alkyl itaconic acid monoester, vinylidene chloride, vinyl acetate, vinyl chloride, allyl glycidyl ether, etc. It can also be used in combination with. In this case, it is preferable that the component of a (meth) acrylic monomer such as an acrylic acid derivative or a methacrylic acid derivative is contained in an amount of 50 mol% or more, and it is particularly preferable that the component of methyl methacrylate is contained.

In the present invention, the cellulose derivative of the component (2) constituting the coating layer A is preferably methyl cellulose or its derivative or ethyl cellulose or its derivative, and particularly methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose, carboxymethyl cellulose, Hydroxylethyl cellulose and the like are preferably used. The content of the cellulose derivative is 5 to 40% by weight, more preferably 1
It is 0 to 30% by weight. The content of cellulose derivative is 5
If it is less than 10% by weight, the outer surface of the coating layer A becomes too flat and blocking is likely to occur. When the content of the cellulose derivative exceeds 40% by weight, the adhesiveness of the coating film decreases, which is not preferable.

In the present invention, the crosslinking component of the component (3) constituting the coating layer A is selected from the group consisting of an oxazoline compound having two or more oxazoline rings, an oxazoline compound or an epoxy compound having two or more epoxy groups. It consists of at least one 2 in the present invention
As the epoxy compound having more than one epoxy group,
The following chemical formula

[0025]

[Chemical 1]

[0026]

[Chemical 2]

[0027]

[Chemical 3]

[0028]

[Chemical 4]

[0029]

[Chemical 5]

[0030]

[Chemical 6]

[0031]

[Chemical 7]

[0032]

[Chemical 8]

[0033]

[Chemical 9]

[0034]

[Chemical 10]

[0035]

[Chemical 11]

[0036]

[Chemical 12]

[0037]

[Chemical 13]

[0038]

[Chemical 14]

[0039]

[Chemical 15]

Those represented by and bisphenol A
A water-soluble or water-dispersible epoxy compound of an addition condensate of and of epichlorohydrin can be exemplified.

The epoxy compound having two or more epoxy groups can be arbitrarily selected from an oxazoline compound having two or more oxazoline rings. The oxazoline compound having two or more oxazoline rings in the present invention is not particularly limited as long as it has an oxazoline ring as a functional group therein, but it contains at least one kind of monomer containing an oxazoline ring. Those comprising two or more oxazoline ring-containing copolymers are preferred. As such an oxazoline compound, JP-A-2-6094
1, JP-A-2-99537, JP-A2-1
The copolymer or its derivative described in Japanese Patent No. 15238, Japanese Patent Publication No. 63-48884 or the like can be used. Specifically, the addition-polymerizable oxazoline represented by the following general formula

[0042]

[Chemical 16]

(However, in the formula, R1, R2, R3, R4
Are each independently hydrogen, halogen, alkyl, aralkyl, phenyl or a substituted phenyl group, and R5 is an acyclic organic group having an addition polymerizable unsaturated bond. ), And a copolymer obtained by copolymerizing at least one other monomer.

Examples of addition-polymerizable oxazolines include 2-vinyl-2-oxazoline and 2-vinyl-4-methyl-2.
-Oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline, 2-
Isopropenyl-4-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline and the like can be used, and one kind or a mixture of two or more kinds thereof can also be used. Of these, 2-isopropenyl-2-oxazoline is industrially readily available and suitable.

In the oxazoline compound, the at least one other monomer used for the addition-polymerizable oxazoline is not particularly limited as long as it is a monomer copolymerizable with the addition-polymerizable oxazoline. For example, methyl acrylate, Acrylic esters or methacrylic acid esters such as methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, acrylic acid-2-ethylhexyl, methacrylic acid-2-ethylhexyl, acrylic acid, methacrylic acid, Unsaturated carboxylic acids such as itaconic acid and maleic acid, unsaturated nitriles such as acrylonitrile and methacrylonitrile, acrylamide, methacrylamide,
Unsaturated amides such as N-methyloacrylamide and N-methylolmethacrylamide, vinyl esters such as vinyl acetate and vinyl propionate, vinyl ethers such as methyl vinyl ether and ethyl vinyl ether,
Olefin such as ethylene and propylene, halogen-containing vinyl chloride, vinylidene chloride, vinyl fluoride, etc.
It is possible to use α, β-unsaturated monomers and α, β-unsaturated aromatic monomers such as styrene and α-methylstyrene, and these may be used alone or in a mixture of two or more kinds. it can.

To obtain an oxazoline compound using the addition-polymerizable oxazoline and at least one other monomer, polymerization may be carried out by an emulsion polymerization method, a solution polymerization method or the like. For example, in the emulsion polymerization method, various methods such as a method in which a polymerization catalyst, water, a surfactant and a monomer are mixed together for polymerization, or a monomer dropping method, a multistage polymerization method, a pre-emulsion method, or the like can be used. Examples of the polymerization catalyst include benzoyl peroxide, t-butyl hydroperoxide, azobisisobutyronitrile, hydrogen peroxide, potassium persulfate, ammonium persulfate, and 2,
A radical polymerization initiator such as 2'-azobis (2-amidinopropane) dihydrochloride can be used. As the surfactant, anionic, cationic, nonionic, amphoteric surfactants, reactive surfactants and the like can be used. The polymerization temperature is usually 0 to 100 ° C., preferably 50 to 80 ° C., and the polymerization time is usually 1 to 100 ° C.
10 hours. Examples of the solvent that can be used in the solution polymerization method include toluene, hexane, methyl ethyl ketone, ethyl cellosolve, methyl cellosolve, ethyl acetate, isopropyl alcohol, and propylene glycol monomethyl ether.
It is also possible to use mixtures of more than one species. Examples of the polymerization initiator used include azobisisobutyronitrile and benzoyl peroxide. The polymerization temperature is 20 to 200 ° C,
It is preferably 40 to 120 ° C.

When the addition-polymerizable oxazoline and other monomers are used to obtain an oxazoline-based crosslinking agent, the addition-polymerizable oxazoline is used in an amount of 0.5 to 8 based on all monomers.
There is no particular limitation as long as it is in the range of 0% by weight or more. If the amount of addition-polymerizable oxazoline used is less than 0.5% by weight, the crosslinking effect due to the oxazoline group tends to be small, and if it exceeds 80% by weight, the affinity with other resins used in combination and the polymerizability of the crosslinking agent itself may decrease. Tends to be inferior.

By the way, the content of the epoxy compound having two or more epoxy groups or the oxazoline compound having two or more oxazoline rings should be 1% by weight or more and 30% by weight or less based on the weight of the coating layer A. Is necessary, and is preferably 2% by weight or more and 25% by weight or less. When the content of the epoxy compound or the oxazoline compound is less than 1% by weight, the coating is soft and thus blocking is likely to occur when the film is wound, in which case the unwinding cannot be performed smoothly. On the other hand, if it exceeds 30% by weight, the coating becomes hard and brittle, the surface roughness increases, and the abrasion resistance decreases.

In the present invention, the material of the inert particles of the component (4) constituting the coating layer A is polystyrene, polystyrene-divinylbenzene, polymethylmethacrylate, methylmethacrylate copolymer, methylmethacrylate copolymer crosslinked product, Any of organic substances such as polytetrafluoroethylene, polyvinylidene fluoride, polyacrylonitrile, benzoguanamine and silicone, and inorganic substances such as silica, alumina, titanium dioxide, kaolin, calcium carbonate, talc and graphite may be used.
Further, a core-shell type particle having a multilayer structure composed of substances having different properties inside and outside the particle may be used. Also,

[0050]

## EQU1 ## The volume shape factor (f) defined by f = v / d ³ (where V is the volume of the inert particles and d is the average particle size) is 0.1 to π /
6 is preferable, and a substantially spherical or rugby ball-shaped ellipsoidal sphere of 0.4 to π / 6 is more preferable.
Particles having a volumetric shape factor (f) of less than 0.1, for example, flaky particles, require a large amount of particles to obtain a desired surface roughness, and the coating film is likely to become brittle.

The average particle size of the inert particles (4) is 10 n.
It is m or more and 100 nm or less, preferably 15 nm or more and 80 nm or less. If this average particle diameter is less than 10 nm, the friction coefficient increases, while if it exceeds 100 nm, the particles tend to fall off from the coating layer. The proportion of the inert particles in the coating layer A is preferably 3% by weight or more and 30% by weight or less, more preferably 5% by weight or more and 25% by weight or less. If this ratio is less than 3% by weight, the winding shape is poor by the time the magnetic recording medium is manufactured, and the running resistance during processing tends to increase. On the other hand, when the content of the inert particles is more than 30% by weight, the particles are likely to be dropped from the coating layer, and the dropped particles may be transferred to the magnetic layer to cause dropout or the like.

Ra of the surface of the coating layer A which is not in contact with the polyester film due to the above-mentioned inert particles or the like needs to be 3 nm or more and 20 nm or less, preferably 5 n.
It is m or more and 15 nm or less. When Ra is less than 3 nm, the handling property during the film forming process of the polyester film or during vapor deposition is significantly deteriorated. On the other hand, when is greater than 20 nm, the coating layer is likely to be scraped, or the shape is easily transferred to the opposite surface when wound into a roll. Further, Rz of the surface of the coating layer A which is not in contact with the polyester film due to the above-mentioned inert particles or the like needs to be 20 nm or more and 200 nm or less. If Rz is less than 20 nm, the handling property during the film forming process of the polyester film or during vapor deposition is significantly deteriorated. On the other hand, when Rz exceeds 200 nm, the coating layer is likely to be scraped off, or the shape is likely to be transferred to the opposite surface when wound into a roll.

In the present invention, the surfactant of the component (5) constituting the coating layer A may be any of anionic type, cationic type and nonionic type, of which the nonionic type is preferred. . Examples of the nonionic surfactant include ester type, ether type, and alkylphenol type. As a specific surfactant, a polyoxyethylene alkylphenyl ether compound is a product name manufactured by NOF CORPORATION, "NONION NS-230", "NONION NS-230".
"S-240", "Same HS-220", "Same HS-24"
0 ", a product name of Sanyo Kasei Co., Ltd.," Nonipol 20
0 "," Nonipol 400 "," Nonipol 500 "," Octapol 400 "and the like, polyoxyethylene alkyl ether compounds are trade names manufactured by NOF CORPORATION," NONION E-230 "," DOK K " -220 "
And “K-230”, and polyoxyethylene ester compounds of higher fatty acids are trade names, “Nonion S-15.4” and “S-S” manufactured by NOF CORPORATION.
"-40" and the like can be preferably exemplified.

The ratio of the above-mentioned surfactant (5) in the coating layer A is 3% by weight or more and 30% by weight or less, preferably 5% by weight or more and 25% by weight or less. If this proportion is less than 3% by weight, the coatability will deteriorate and the adhesion of the backcoat layer will decrease. On the other hand, if it exceeds 30% by weight, the particles tend to fall off from the coating layer.

In the present invention, the resin (6) having fluorine or a silicone compound as a copolymerization component is used for the coating layer A as 1
It is preferable that the content is not less than 20% by weight. This resin preferably has a combination of a highly polar group and a hydrophobic group in the molecule. Further, it is not an adhesive type polymer, but it is solidified by evaporation of water or a solvent after coating. It is preferable that the polar group contains a hydroxyl group, an acid group, an ether group, an ester group, an epoxy group, a sulfonic acid group, a urethane bond or the like, and the hydrophobic group contains an aliphatic chain or an aromatic chain. 1 mol% or more within 1 or within the hydrophobic group 1
It is preferable to have 5 mol% or less as a copolymerization component.
Fluorine or silicone compound-containing polyurethane, fluorine or silicone compound-containing polyester ether copolymer, fluorine or silicone compound-containing water-soluble polyester copolymer, acrylic copolymer, polyethylene glycol / sulfonic acid alkali metal salt-containing fluorine or silicone compound A polyester copolymer or the like can be used. Among the polyester copolymers composed of dicarboxylic acid and glycol, those having 5-sodium sulfoisophthalic acid salt, fluorinated polyethylene or polydimethylsiloxane chain-containing isophthalic acid, and ethylene glycol or diethylene glycol or both as components are particularly preferable.

The resin (6) having a fluorine or silicone compound as a copolymer component is contained in the coating in an amount of 1% by weight or more and 20% or more.
It is contained in an amount of not more than wt%, preferably 2 to 15 wt%. If it is less than 1% by weight, blocking tends to occur,
When it is 20% by weight or more, the coating becomes too soft, and the sharpness of the coating decreases, which is not preferable.

A silane coupling agent may be added to the coating in order to further increase the adhesion between the coating and the polyester film. The silane coupling agent is an organosilicon monomer having two or more different reactive groups in its molecule, one of the reactive groups is a methoxy group, an ethoxy group, a silanol group, etc. The reactive group is a vinyl group, a methacrylic group, an amino group, a mercapto group or the like. The reactive group is selected such that it bonds with the side chain, terminal group and polyester of the polymer blend constituent, but as the silane coupling agent, vinyltrichlorosilane, vinyltriethoxysilane, aminoethylaminopropylmethyldimethoxysilane, aminopropyltriethoxysilane. Etc. can be applied.

In the present invention, the coating layer A may optionally contain other components, such as a stabilizer, a dispersant, a UV absorber, a thickener and a release agent, as long as the effects of the present invention are not impaired. Etc. can be contained.

<Coating Layer B> On the surface of the polyester film for a magnetic recording medium of the present invention which is not in contact with the coating layer A (hereinafter sometimes referred to as B surface), a slippery or magnetic layer, particularly a vapor deposition layer is formed. It is preferable to provide the coating layer B for the purpose of easy adhesion. The coating layer B is not specified, but may be the same coating as the coating layer A in the present invention, for example. Coating layer B
It is preferable that Ra on the surface not in contact with the polyester film is 0.1 nm or more and 3 nm or less. Ra
Is less than 0.1 nm, sticking to the head is likely to occur when the magnetic recording medium is used. On the other hand, when Ra exceeds 3 nm, the electromagnetic conversion characteristics tend to deteriorate. Therefore, the inert particles added to the coating layer B have an average particle size of 5 nm or more and 50 nm or more.
nm or less, and the addition amount is preferably 1% by weight or more and 20% by weight or less. The surface of the coating layer B not in contact with the polyester film has Rz of 10 nm or more and 50 nm or more.
Is preferred.

<Thickness> The laminated polyester film of the present invention preferably has a thickness of 2 μm or more and less than 7 μm, and more preferably 3 μm or more and 6 μm or less. If the film thickness exceeds 7 μm, the length of the magnetic tape that can be stored in the cassette becomes insufficient, resulting in insufficient storage capacity.
On the other hand, when the thickness is less than 2 μm, the film forming stability during film production decreases, and even if the film can be commercialized, permanent force of the film is generated due to the force applied when the magnetic tape is started or stopped, and the durability is satisfied. In addition, since the tape has poor rigidity and causes poor head contact, it is not preferable.

<Magnetic Recording Medium> In the polyester film for a magnetic recording medium according to the present invention, a ferromagnetic metal thin film layer of a magnetic layer is provided on the surface of the polyester film opposite to the coating layer A, that is, on the coating layer B if necessary. However, a known material can be used for forming the metal thin film,
There is no particular limitation. This metal includes iron, cobalt,
A ferromagnetic material of nickel, chromium or an alloy thereof is preferable. The metal thin film can be formed by a vacuum vapor deposition method, a sputtering method, or the like. The metal thin film layer preferably has a thickness of 50 to 300 nm.

<Backcoat Layer> A solution comprising solid fine particles and a binder on the surface of the polyester film for a magnetic recording medium of the present invention which is not in contact with the polyester film on the surface of the coating layer A, and various additives are added if necessary. You may provide the backcoat layer formed by apply | coating. Known solid fine particles, binders, and additives can be used and are not particularly limited, but the thickness of the back coat layer is preferably 0.3 to 1.5 μm.

<Production Method of Film> The polyester film for a magnetic recording medium of the present invention is a polyester film which has been stretched in one direction in a usual polyester film (base film) production process comprising melt molding, biaxial stretching and heat setting. It can be produced by applying the coating liquid for forming the coating layer A on one surface of the film, if necessary coating the coating liquid for forming the coating layer B on the other surface and drying, and then stretching in the perpendicular direction and heat setting. . In the case of simultaneous biaxial stretching, it can be manufactured by applying a coating solution to an unstretched film, simultaneously biaxially stretching and heat-setting. A known method can be applied as a method of applying the coating liquid. For example, a roll coating method, a gravure coating method, a roll brushing method, a spray coating method, an air knife method, an impregnation method, a curtain coating method or the like can be applied alone or in combination. The solid content concentration of the coating solution is 0.1 to 1 in the case of sequential stretching.
It is preferably 0% by weight, more preferably 0.3 to 5% by weight. In the case of simultaneous biaxial stretching, 0.5 to 20% by weight is preferable. Stretching is at least 3 times or more in the uniaxial direction, and the area ratio is 8 to 3
It is preferable to stretch 0 times, further 12 to 25 times.

[0064]

EXAMPLES The present invention will be further described based on examples. The method of measuring the film characteristic value and the method of evaluating the effect in the present invention are as follows. (1) Average particle diameter of particles The equivalent spherical diameter of the particles at the point of 50% by weight of all particles determined by the light scattering method is defined as the average particle diameter.

(2) Volume Shape Factor A photograph of each particle was taken with a scanning electron microscope at a magnification corresponding to the size of the particle, and the maximum diameter of the projection surface and the volume of the particle were calculated using the image analysis processor Luzex. Then, it is calculated by the following formula.

[0066]

[Number 2] f = in V / d ³ formula, f is the volume shape factor, V is the particle volume (μm ^3),
d represents the maximum diameter (μm) of the projection surface.

(3) Thickness of coating layer A small piece of the film is fixedly molded with an epoxy resin, and a microtome is used to prepare an ultrathin section (cut parallel to the flow direction of the film) with a thickness of about 60 nm. With an equivalent electron microscope (H-800 manufactured by Hitachi, Ltd.),
Obtain the layer thickness from the boundary line of the layers.

(4) Surface Roughness Ra (root mean square roughness) and Rz (10-point average roughness) calculated under the following conditions using a J scanner of an atomic force microscope Nano Scope III AFM manufactured by Digita1 Instruments. Is measured under the following conditions. Probe: Single bond silicon sensor Scan mode: Tapping mode Number of pixels: 256 × 256 Data point Scan speed: 2.0 Hz Measurement environment: Room temperature, in air Scan range: Coating layer A forming surface; 10 μm × 10 μm Coating layer B forming surface 2 μm × 2 μm

(5) Anti-blocking property The surface of the two films on which the coating layer A is formed and the other surface (B
Surface) on top of each other, and this is first treated in an atmosphere of 50 ° C. × 70% RH for 10 hours under a load of 1 N / mm ² .
Next, it is treated under a load of 15 N / mm ² for 100 hours, and 5c.
It is cut into strips of m width and evaluated by the peel strength (mN / 5 cm) of the portion to which a load is applied by a tensile tester. In addition,
The evaluation is based on the peel strength and the following criteria. ◯: 0 to 50 Δ: 50 to 100 ×: 100 to breakage

(6) Coefficient of friction of film (μs) A fixed glass plate is placed under the two superposed films, and the film under the superposed films (the film in contact with the glass plate) It is pulled by a low-speed roll (about 10 cm / min), and the detector is fixed to one end of the upper film (the end opposite to the pulling direction of the lower film) to detect the tensile force at the start between the films. . The thread used at that time weighs 1 kg and has a lower area of 100.
Use the one with cm ² . The friction coefficient (μs) is calculated by the following equation. μs = tensile force at start (kg) / load of 1 kg The evaluation is based on the following criteria. ○: less than 0.7 △: 0.7 or more and less than 0.80 x: 0.80 or more

(7) Scraping resistance A razor blade was applied to a film slit to a width of 12.7 mm under the conditions of an accuracy of 90 ° and a depth of 0.5 mm, a tension of 60 g and a speed of 60 m / The width in the depth direction of the shavings adhering to the blade of the razor when running for 50 m per minute is determined by taking a micrograph (× 160). The width of the shavings in the depth direction is judged as follows. The smaller the depth of the shavings in the depth direction, the better the sharpness. ○: less than 0.15 mm △: 0.15 mm or more less than 0.30 mm ×: 0.30 mm or more

(8) Production of magnetic tape and evaluation of characteristics On the surface of the coating layer B of the polyester film, a cobalt-oxygen thin film having a thickness of 110 nm was formed by vacuum evaporation, and then on the cobalt-oxygen thin film layer, a sputtering method was used. To form diamond-like carbon with a thickness of 10 nm,
Further, a fluorinated carboxylic acid-based lubricant is sequentially provided, and subsequently, a back coat layer made of carbon black, polyurethane, and silicone is provided on the surface of the coating layer A to a thickness of 500 nm, slitted to a width of 8 mm by a slitter, wound on a commercially available reel, and magnetically coated. I made a tape. Electromagnetic conversion characteristics are commercially available Hi
Video S using 8 system 8mm video tape recorder
Calculate the / N ratio. For the S / N measurement, a signal was supplied from a TV test signal generator, a video noise meter was used, and a commercially available standard Hi8ME tape was used for zero decibel (d).
B) will be compared and examined. ◯: Compared to commercially available tape +2 dB or more Δ: Compared to commercially available tape -2 dB or more to less than +2 dB X: Compared to commercially available tape Less than -2 dB

[Example 1] Dimethyl 2,6-naphthalenedicarboxylate and ethylene glycol were added, manganese acetate was added as a transesterification catalyst, antimony trioxide was used as a polymerization catalyst, and phosphorous acid was added as a stabilizer. Polymerization was performed to obtain polyethylene-2,6-naphthalenedicarboxylate containing substantially no inert particles. After drying the pellets at 170 ° C. for 6 hours, the pellets were fed to an extruder and melted at 305 ° C. This molten polymer was filtered by a known method, extruded into a sheet form from an extruder, and cooled and solidified on a casting drum to prepare an unstretched film. The unstretched film thus obtained is 1
Preheated at 20 ℃, 15m between low speed and high speed rolls
m from above and heated by an infrared heater at 900 ° C. to be stretched in the longitudinal direction by 3.7 times, and subsequently, an aqueous solution for the coating layer A and the coating layer B having the compositions shown below is dried to form the coating layer. The thickness of A is 15 nm and the thickness of the coating layer B is 5.2.
It was applied to a polyester film so that the thickness would be nm.

Composition of coating layer A: (1) Acrylic-polyester resin (A): 55% by weight Polyester component: isophthalic acid (95 mol%), 5
-Sodium sulfoisophthalic acid (5 mol%) / ethylene glycol (92 mol%), diethylene glycol (8 mol%)-Acrylic resin component: methyl methacrylate (90 mol%), glycidyl methacrylate (10 mol%)-polyester component / Mole ratio of acrylic resin component = 3 /
7 (2) Cellulose derivative (A): 15 wt% -Hydroxyethylmethylmethylcellulose (3) Oxazoline compound (A): 5 wt% -Nippon Shokubai Co., Ltd. polymer cross-linking agent CX-WS120 (4) Acrylic resin fine particles (A): 10% by weight-Average particle size 50 nm-Volume shape factor 0.50 (5) Silicone compound copolymer water-soluble polyester (A): 5% by weight-Acid component (terephthalic acid 70 mol%, 5-sodium) 1: 1 copolymer of sulfoisophthalic acid (10 mol%, polydimethylsiloxane group-substituted isophthalic acid 20 mol%) and ethylene glycol (6) Surfactant (A): 10% by weight-Nonion NS manufactured by NOF Corporation -240

Composition of coating layer B: (1) Acrylic-polyester resin: 75% by weight Polyester component: terephthalic acid (70 mol%), isophthalic acid (18 mol%), 5-sodium sulfoisophthalic acid (12 mol%) ) / Ethylene glycol (92 mol%), diethylene glycol (8 mol%)-Acrylic resin component: methyl methacrylate (80 mol%), glycidyl methacrylate (15 mol%), n-
Butyl acrylate (5 mol%)-Polyester component / acrylic resin component molar ratio = 3 /
7 (2) Acrylic resin fine particles: 5 wt% -Average particle size 20 nm-Volume shape factor 0.50 (3) Surfactant: 20 wt% -Nonion NS-240 manufactured by NOF Corporation

Subsequently, the coated polyester film is supplied to a stenter, stretched 4.9 times in the transverse direction at 150 ° C., and further stretched 1.14 times at 200 ° C. while being stretched 5 times.
The coating layer was crosslinked by heat treatment for 2 seconds to obtain a biaxially oriented laminated film having a thickness of 4.7 μm. The surface of the coating layer B of this laminated film which is not in contact with the polyester film is R
a was 1.5 nm and Rz was 30 nm.

Then, a cobalt-oxygen thin film having a thickness of 110 nm was formed on the surface of the coating layer B of the laminated film which was not in contact with the polyester film by vacuum vapor deposition. Next, on the cobalt-oxygen thin film layer, diamond-like carbon was formed with a thickness of 10 nm by a sputtering method. Further, on the surface of the coating layer A of the laminated film which is not in contact with the polyester film, a back coat layer made of carbon black, polyurethane or silicone is applied by 500.
nm is provided. Then, the laminated body provided with the diamond-like carbon and the back coat layer is slid to a width of 8 mm.
Slit to mm and wound on a reel to make a magnetic tape. The properties of the obtained laminated film and magnetic tape are shown in Table 2.

Example 2 The coating layer A in Example 1 was used.
A laminated film having a thickness of 4.7 μm and a magnetic tape were obtained in the same manner as in Example 1 except that the composition was changed to the content shown in Table 1. The properties of the obtained laminated film and magnetic tape are shown in Table 2.
Shown in.

[Example 3] Dimethyl terephthalate and ethylene glycol were added, manganese acetate was used as a transesterification catalyst, antimony trioxide was used as a polymerization catalyst, and phosphorous acid was added as a stabilizer. Polyethylene terephthalate (P containing no inert particles)
ET).

170% of this polyethylene terephthalate
After being dried at ℃ for 3 hours, it is fed to an extruder and melted at a temperature of 280-280
It was melted at 300 ° C., extruded into a sheet from a die, and rapidly cooled to obtain an unstretched film having a thickness of 82 μm.

The obtained unstretched film was preheated, further stretched 3.2 times in the machine direction at a film temperature of 95 ° C. between low-speed and high-speed rolls, and rapidly cooled, and then on one surface of the machine-stretched film. A water-soluble coating solution having the same composition of the coating layer A as in Example 1 was applied to the other surface in the same manner as in Example 1, and a water-soluble coating solution having the same composition of the coating layer B as in Example 1 was subsequently applied to the stenter. It was supplied and stretched 4.1 times in the transverse direction at 110 ° C. The obtained biaxially stretched film was heat set with hot air at 220 ° C. for 4 seconds to obtain a laminated film having a thickness of 6.0 μm. The obtained laminated film was used as a magnetic tape by repeating the same operation as in Example 1. The properties of the obtained laminated film and magnetic tape are shown in Table 2.

Example 4 In the production of the polyester film of Example 1, 0.2 weight of polyethylene-2,6-naphthalene dicarboxylate containing substantially no inert particles and silica having an average particle size of 200 nm was used. % Of the polyethylene-2,6-naphthalenedicarboxylate polymer containing inert particles contained therein was changed to a polyester film laminated by coextrusion at a ratio of thickness 3: 1, and substantially no inert particles were contained. Polyethylene-2,6-
The same operation as in Example 1 was repeated except that the coating layer B was provided on the surface layer made of naphthalene dicarboxylate, the coating layer A was provided on the surface layer made of the latter, and the composition of A was changed to the content shown in Table 1. Thus, a laminated film and a magnetic tape were obtained. The properties of the obtained laminated film and magnetic tape are shown in Table 2.
Shown in.

[Comparative Example 1] In Example 1, the coating layer A was used.
A laminated film having a thickness of 4.7 μm and a magnetic tape using the same were obtained in the same manner as in Example 1 except that no coating agent for coating was applied. The properties of the obtained laminated film and magnetic tape are shown in Table 2.

[Comparative Examples 2 to 7] A laminated film having a thickness of 4.7 μm was prepared in the same manner as in Example 1 except that the composition of the coating material for the coating layer A was changed to that shown in Table 1. A magnetic tape using was obtained. The properties of the obtained laminated film and magnetic tape are shown in Table 2.

[0085]

[Table 1]

[0086]

[Table 2]

In Tables 1 and 2, PEN is polyethylene-2,6-naphthalene dicarboxylate, PEN.
ET is polyethylene terephthalate, acrylic-polyester (a) is the example of Example 1, and copolyester (b) is (terephthalic acid / isophthalic acid / 5-sodium sulfoisophthalic acid) / (ethylene glycol / bisphenol A propion oxide 2). Molar adduct) =
(97/1/2) / (60/40) (molar ratio), Cellulose derivative (c) is hydroxyethylmethylmethylcellulose, Oxazoline compound (d) is Nippon Shokubai Co., Ltd. Polymer crosslinking agent CX-WS120, Epoxy Compound (e) is DINACOL EX-31 manufactured by Nagase & Co., Ltd.
4. Inert particles (f) are acrylic resin particles (average particle size 5
0 nm), inert particles (g) are spherical silica (average particle size 5
nm), inert particles (h) are spherical silica (average particle size 15
0 nm), fluorine or a silicon compound (i) is the product of Example 1 and the surfactant (j) is the product of Example 1.

As is clear from Table 1, the laminated film for a magnetic recording medium according to the present invention has a low friction coefficient, there is no blocking between the films, and it is excellent in abrasion resistance. Excellent in. In contrast,
Those which do not satisfy the requirements of the present invention cannot satisfy these characteristics at the same time.

[0089]

According to the present invention, it is possible to provide a polyester film which is excellent in workability during film formation and processing, blocking resistance and abrasion resistance and which is useful as a base film for a high recording density magnetic recording medium. .

Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C09D 133/00 C09D 133/00 163/00 163/00 167/00 167/00 183/04 183/04 // C08L 67 : 02 C08L 67:02 F-term (reference) 4F006 AA35 AB03 AB12 AB24 AB34 AB35 AB43 AB52 AB65 BA12 CA02 4F100 AA37 AB01C AB15 AH02H AH03B AH07B AH07H AJ04B AK01B AK17B AK25B AK41A AK41B AK42A AK51 AK52 AK52B AL01B BA02 BA03 BA07 BA10A BA10C CA02B CA18B DD07B DE01B EH17 EH46 EH66 EJ05 EJ38 GB41 JA20A JG06C JK15 JK16 JL00 JL01 JM02C YY00A YY00B 4J038 BA101 CG001 CK022 CP071 CP121 CQ001 DB012 DD001 DL102 GA12 CB01 CB01CB01 CB01 CB05 NA01 5A05 NA11 P11B006

Claims (11)

[Claims] 1. A coating layer A on one side of a polyester film.
A film obtained by laminating the coating layer A,
At least one crosslinking component selected from the group consisting of (1) acrylic-polyester resin, (2) cellulose derivative, (3) oxazoline compound having two or more oxazoline rings, and epoxy compound having two or more epoxy groups. , (4) inert particles and (5) a surfactant as a main component, and the content of the crosslinking component (3) is 1% by weight or more based on the weight of the coating layer A 30
Root mean square roughness (Ra) by AFM of the surface of the coating layer A not in contact with the polyester film, which is less than or equal to% by weight.
And a 10-point average roughness (Rz) of more than 3 nm and 20 nm or less and 20 nm or more and 200 nm or less, respectively. 2. The laminated film for a magnetic recording medium according to claim 1, wherein the content of the cellulose derivative is 5% by weight or more and 40% by weight or less based on the weight of the coating layer A. 3. The content of the acrylic-polyester resin is 30% by weight or more and 90% by weight based on the weight of the coating layer A.
The laminated film for a magnetic recording medium according to claim 1, which is not more than wt%. 4. The average particle diameter of the inert particles is 10 nm or more and 100 nm or less, and the content thereof is 3% by weight or more and 30% by weight or less based on the weight of the coating layer A.
A laminated film for a magnetic recording medium as described above. 5. The coating layer A contains a resin containing fluorine or a silicone compound as a copolymerization component in an amount of 1% by weight or more and 2
The laminated film for a magnetic recording medium according to claim 1, which contains 0% by weight or less. 6. The root mean square roughness (Ra) and the 10-point mean roughness (Rz) by AFM of the surface of the polyester film which is not in contact with the coating layer A are 0.1 nm or more and 3 nm or less and 10 nm or more and 50 nm, respectively. The laminated film for a magnetic recording medium according to claim 1, which is as follows. 7. The polyester film is a film made of polyethylene terephthalate or polyethylene-2,6-naphthalene dicarboxylate.
A laminated film for a magnetic recording medium according to any one of items 1 to 6. 8. The thickness of the polyester film is 2 μm
The laminated film for a magnetic recording medium according to any one of claims 1 to 7, which has a thickness of at least 7 μm. 9. The laminated film for a magnetic recording medium according to claim 1, wherein the surface of the coating layer A which is not in contact with the polyester film is the surface of the magnetic layer on which the ferromagnetic metal thin film layer is formed. 10. The laminated film for a magnetic recording medium according to claim 1, which is used for a magnetic tape of a digital recording system. 11. A magnetic recording medium using the laminated film for a magnetic recording medium according to claim 1.